1. Field of the Invention
The present invention relates to an image capturing device and a network camera system that obtain a plurality of images by performing image capturing while slightly displacing optical images formed on a light-receiving surface of an image capturing element relative to the image capturing element.
2. Description of Related Art
An image capturing device employs an image capturing element in which pixels are arranged in a two-dimensional matrix pattern. The resolution of the image capturing element is limited because it depends on the size of pixels and the number of pixels in the image capturing element. To generate images having a higher resolution than that of the image capturing element itself, super-resolution processing is performed after so-called pixel offset (optical shift) in which a plurality of original images are captured while optical images formed on a light-receiving surface of the image capturing element are slightly displaced relative to the image capturing element.
Such a technology of pixel offset requires an optical shift mechanism for slightly displacing the optical images and the image capturing elements with respect to each other (see Related Art 1).
For example, a parallel plate is provided between the image capturing element and a lens unit that forms images on the image capturing element based on light from an object. The parallel plate is inclined with respect to the optical axis of the lens unit, and the position of the optical image on a light-receiving surface of the image capturing element is displaced by rotating the parallel plate around the optical axis (see Related Art 2 and Related Art 3).    Related Art 1: Japanese Patent Application Publication No. 2008-306492    Related Art 2: Japanese Patent Application Publication No. 2000-125170    Related Art 3: Japanese Patent Application Publication No. 2000-278614
In the conventional art, however, when the angle of the parallel plate with respect to the optical axis is varied by swing or the like due to backlash or the like in a supporting mechanism for supporting the parallel plate to be driven in rotation, an optical shift amount (shift position) is significantly affected and a precision of the optical shift mechanism is deteriorated. When the optical shift amount is not precise, the calculation cost in the super-resolution processing is enormous.